Method and apparatus for forming a multi-lobed winding for the stator of an alternator

ABSTRACT

Method and apparatus for forming a multi-lobed winding for the stator of an alternator, particularly for use in the automotive field and of the type comprising turns defining a star-shaped configuration having a plurality of radial lobes alternated with hollows.

This is a continuation of application No. 08/970,480, filed Nov. 14,1997, now U.S. Pat. No. 5,881,778, which is incorporated by referenceherein.

BACKGROUND OF THE INVENTION

The present invention relates to a method and an apparatus for forming amulti-lobed winding for the stator of an alternator, particularly foruse in the automotive field and of the type comprising turns defining astar-shaped configuration having a plurality of radial lobes alternatedwith hollows.

A method and an apparatus for forming a multi-lobed winding for thestator of an alternator are disclosed, for example, in Italian patent1,157,040, corresponding to Barrera, Apparatus For Forming Stator CoilsOf Dynamo Electric Machines, U.S. Pat. No. 4,512,376, both of which areincorporated herein by reference.

Typically, in the case of a three-phase alternator for automotive use,each stator is provided with a winding including three multi-lobed coilsangularly shifted relative to each other. The coils are formed atdifferent stages by the forming machine, and each coil has two wireterminal ends. Each of the three multi-lobed coils constituting one ofthe three phases of the winding is split into two semi-coils orsemi-phases which are angularly shifted relative to each other by onelobe, so that the lobes of one semi-phase are opposite to the hollowsbetween the lobes of the other semi-phase.

According to the prior art, the two semi-phases of each coil are made bythe forming machine at two subsequent stages by cutting the suppliedwire between one forming stage and the other, so that each semi-phase ofthe three winding phases in the finished winding inserted into thestator has a pair of terminal ends. This results in a total of twelveterminal ends.

A stator winding of undulatory type with a single continuous wire,including two multi-lobed coils shifted relative to each other by onelobe, has already been proposed. (See, for example, Taji et al.,Armature Of A.C. Generator For A Car And Method Of Manufacturing TheSame, U.S. Pat. No. 4,857,787 and parallel European patent 209,091, bothof which are incorporated herein by reference). This method initiallyinvolves forming a single multi-lobed coil which is then split into twocoils, without cutting the wire portion connecting them, one of thecoils being overlapped on the other in at overturied position. Thisadditional operation involves wasted time and a resulting decrease inthe productivity of the machine.

In view of the foregoing, it would be desirable to provide a method andapparatus in which the final required configuration of the winding isobtained without additional operations after winding the wire by anapparatus which requires very small changes with respect, for example,to the apparatus taught in Italian patent 1,157,040 and correspondingU.S. Pat. No. 4,512,376.

It would also be desirable to provide a method and an apparatus forforming a multi-lobed winding for the stator of an alternator whichenable the two semi-phases of each winding phase to be madecontinuously, without cutting the wire at the end of the formingoperation of the first semi-phase, so as to simplify the operationswhich are necessary for forming the winding, as well as to obtain afinished winding with a lower number of terminal ends.

It would also be desirable to provide a method and an apparatus by whichmulti-lobed windings constituted by a plurality of coaxial superimposedmulti-lobed coils having their lobes angularly shifted relative to eachother can be obtained continuously.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method andapparatus in which the final required configuration of the winding isobtained without additional operations after winding the wire by anapparatus which requires very small changes with respect, for example,to the apparatus taught in Italian patent 1,157,040 and correspondingU.S. Pat. No. 4,512,376.

It is also an object of the present invention to provide a method and anapparatus for forming a multi-lobed winding for the stator of analternator which enable the two semi-phases of each winding phase to bemade continuously, without cutting the wire at the end of the formingoperation of the first semi-phase, so as to simplify the operationswhich are necessary for forming the winding as well as to obtain afinished winding with a lower number of terminal ends.

It is yet another object of the present invention to provide a methodand an apparatus by which multi-lobed windings constituted by aplurality of coaxial superimposed multi-lobed coils having their lobesangularly shifted relative to each other can be obtained continuously.

These and other objects and advantages of the invention are accomplishedby forming a multi-lobed winding for the stator of an alternator. In afirst stage, a first multi-lobed coil is formed, by winding acontinuously fed wire in a first direction. In a second stage a secondmulti-lobed coil, axially superimposed to the first coil, is formed,without cutting the wire being fed, by winding the wire in the oppositedirection and arranging the second coil at a position angularly shiftedrelative to the first coil. The second coil has its lobes at the sameangular positions of the hollows of the first coil. The wire portionconnecting the two coils is bent where the wire reverses its windingdirection so as to form a loop, following an annular path matching theprofile of a lobe of one of the two coils for one part and the profileof a hollow of the other coil opposite to the lobe for another part.

The invention thus provides a multi-lobed winding for the stator of analternator, particularly for use in the automotive field and of the typecomprising turns defining a star-shaped configuration having a pluralityof radial lobes alternated with hollows.

The invention also provides a winding comprising two coaxialsuperimposed multi-lobed coils with lobes angularly shifted relative toeach other. There is no interruption of the wire constituting thewinding and, therefore, the winding has only two terminal ends. Thus,the method and the apparatus according to the invention simplify theforming operation as well as provide a stator winding with a number ofterminal ends reduced by a factor of two.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparentfrom the description which follows with reference to the annexeddrawings, given purely by way of non-limiting example, in which:

FIG. 1 is a perspective view from below of a rotating unit forming partof a preferred embodiment of the apparatus according to the invention,where the device for receiving the multi-lobed coils formed on therotating unit is also shown in a perspective view from above, thereceiving device also functioning, according to a known technique, as adevice for inserting the multi-lobed coils into the slots of a stator ofan alternator at a subsequent stage,

FIGS. 2-6 are diagrammatic plan views of the different forming stages ofthe multi-lobed winding, according to the invention,

FIG. 7 is a perspective view of a multi-lobed coil comprising twosemi-phases angularly shifted relative to each other, obtained accordingto the invention, which has been shown in a deformed condition in orderto more clearly show the wire portion connecting the two semi-phases,

FIG. 8 is a plan view of the coil of FIG. 7,

FIG. 9 is a diagrammatic view of a winding obtained by the inventioninserted into the slots of a stator of an alternator,

FIG. 10 is a perspective view from below of a rotating unit forming partof the apparatus according to the invention, where the device forreceiving the multi-lobed coils formed on the rotating unit is alsoshown,

FIGS. 11 and 12 are diagrammatic plan views of the apparatus at twodifferent stages of the forming operation of the multi-lobed windingaccording to the invention;

FIG. 13 is a partial diagrammatic plan view of the apparatus; and

FIG. 14 is a partial view of the apparatus of FIG. 13 along A--A at adifferent stage of the forming operation of the multi-lobed winding.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, numeral 1 designates the rotating unit of amachine for forming multi-lobed coils which are to be inserted into theslots of a stator of a three-phase alternator for automotive use. Themachine comprising rotating unit 1 is of the general type described in,for example, Italian patent 1,157,040 and parallel U.S. Pat. No.4,512,376. Therefore, a detailed description of the general structure ofthe machine is not repeated herein, since it is illustrated in the aboveidentified patents.

In a way similar to that practiced in the prior art, the rotating unit 1is used in order to wind thereon a wire W fed by a wire feeding device(not shown in FIG. 1) which has a delivery tube 2 outlet mouth at thearea indicated by 2 in FIG. 1.

The rotating unit 1 carries six forming elements 3 on which the wire fedfrom delivery tube 2 outlet mouth is wound, as a result of the rotationof rotating unit 1, so as to form an hexagonal coil C_(P1) (see alsoFIG. 2). One of the forming elements 3 is provided with a clamp te holdthe starting end W_(o) of the wire.

The forming elements 3 are carried by slides 4 which are radiallyslidably mounted relative to axis 5 of rotation of unit 1. The formingelements 3 are positioned between a first radially outer end position(shown in FIGS. 1 and 2) and a second radially inner end position (shownin FIG. 3).

In the first stage of the forming method, the forming elements 3 are attheir outer positions (FIG. 2) so as to enable, as already indicated, ahexagonal coil C_(P1) having a relatively large diameter to be formed,as shown in FIG. 2.

The machine according to the invention has six pushing members 6included on the rotating unit 1 and radially movable relative to theaxis of rotation 5 to push radially inwardly the central parts of thesides of the hexagonal coil formed in the first stage of the method(FIG. 2). Therefore, pushing members 6 are also carried by slides,designated by 7 in FIG. 1, which are slidably mounted on radial guidescarried by the rotating unit 1.

When the hexagonal coil C_(P1) has been formed with the required numberof turns, the rotating unit 1 is stopped and the pushing members 6 aremoved towards the radially inner position shown in FIG. 3, so as toengage the sides of the polygonal coils C_(P1), transforming the latterinto a multi-lobed or star-shaped coil C₁ (FIG. 3). During thisoperation, the forming elements 3 also move radially inwardly whileproviding some resistance to the tension exerted by the wire of the coilas a result of the pressure applied by pushing members 6. According tothe prior art, this resistance is obtained by connecting the formingelements 3 by flexible metal cables to a fluid cylinder having a chamberwhich ciecreases in volume during the radial inward movement of theforcing elements 3 and which is connected to a discharge reservoirthrough a throttled passage. Since these details of construction areknown from the above mentioned patents, they are not repeated herein.However, it is clear that any other device of known type adapted toprovide the above mentioned effect of controlled yielding of the formingelements 3 may be used.

With reference to FIGS. 1-3, rotating unit 1 is also provided with acircumferential set of six flat fingers 8 which are at angular positionscorresponding to the forming elements 3. The elements 8 are carried bythe rotating unit 1 and are in radially fixed positions relativethereto, in contrast to forming elements 3 and pushing members 6. Asshown in FIGS. 2 and 3, elements 8 are located at a radially innerposition adjacent the innermost radial position of the respectiveforming elements 3. Therefore, during the shaping operation of the coilC_(P1), which provides the multi-lobed coil C₁, the elements 8constitute a further reference for the width of each lobe L of themulti-lobed coil C₁.

As taught in the art, a device 9 is provided under rotating unit 1 forreceiving the multi-lobed coils after they have been formed and forinserting them (in a subsequent stage of operation not shown in thedrawings) into the slots of a stator of an alternator. The insertingdevice 9 comprises a circumferential set of twelve blades 10 separatedby longitudinal slots 11 and carried by a supporting structure 12 whichcan be rotated around the axis of rotation 5 by an electric motor (notshown). The electric motor and the associated transmission for rotatingunit 1 and inserting device 9 are not shown herein in detail since theyare similar to what is provided in the prior art.

It is to be noted that in FIG. 1, for convenience of illustration, theinserting device 9 has been shown at a position axially spaced apartform rotating unit 1, whereas they are positioned immediately verticallyin practice.

As already described, the rotating unit 1 is stopped and the pushingmembers 6 are caused to advance to form the multi-lobed coil C₁ afterforming polygonal coil C_(P1) (FIG. 2). At this time, this multi-lobedcoil C₁ is discharged from the rotating unit 1 over inserting device 9by a coil removing device of conventional type carried by rotating unit1 and adapted to be lowered axially from a retracted position up to aposition in which it engages the multi-lobed coil C₁ and pushes thiscoil downwardly making it slide from the forming elements 3 and causingthe radial portions of the coil to be inserted into the slots 11, sothat the lobes L and the hollows V between the lobes of the multi-lobedcoil C₁ are located alternatively at the outside and the inside of thecircumferential set of blades 10, as shown in FIG. 1. In FIG. 1, thecoil removing device is not shown, since it is in its raised position,retracted inside the rotating unit 1. This coil removing devicecomprises, according to the prior art, a circumferential set of blades13 (see FIG. 2) extending downwardly from an upper ring, similar to whatis shown in FIG. 1 for elements 8. As a result of its lowering movement,the coil removing device starts with its base ring in engagement withthe radial portions of the multi-lobed coil C₁ and pushes this coildownwardly, causing it to slip out of the forming elements 3 and intoslots 11 of the inserting device 9, as shown in FIG. 1.

In the conventional machine, either immediately before or immediatelyafter discharging the multi-lobed coil C₁ on the inserting device 9, thewire being fed is cut, so that the coil arranged on the inserting device9 has two terminal ends. Therefore, in the method according to the priorart, the rotating unit may be rotated again to provide a secondmulti-lobed coil which is then discharged onto the inserting device 9 atan angularly shifted position, so as to obtain, for example, the twosemi-phases of a phase of the winding, with a total of four terminalends.

In contrast to the prior art, according to the present invention, afterthe first multi-lobed coil C₁ has been discharged on the insertingdevice 9, the wire being fed is not cut and the forming of a newpolygonal coil is instead initiated by rotating the rotating unit 1 in adirection of rotation opposite to that of the previous forming stage, asshown in FIGS. 4 and 5. Specifically, in the forming stage shown in FIG.2, the rotating unit is rotated in the direction indicated by arrow A inFIG. 2. In the forming stage shown in FIG. 5, the rotating unit isrotated in the opposite direction B, i.e. in an anti-clockwisedirection.

Naturally, since the wire portion which connects the previously formedmulti-lobed coil C₁ (located on the inserting device 9) to the polygonalcoil C_(P1) (which is being formed during the stage shown in FIG. 5,corresponding as well to the condition shown in FIG. 1) is notinterrupted, it is necessary that the inserting device 9 is also rotatedat the same speed during the rotation of rotating unit 1 during thesecond forming stage, so that the rotating unit 1 and the insertingdevice 9 always remain at the same relative positions. This is donepreferably by controlling the electric motors which drive the rotatingunit 1 and the inserting device 9 in synchronism with each other.Alternatively, a releasable mechanical coupling between the rotatingunit 1 and the inserting device 9 may be provided, thereby allowing thesame motor to be used to drive the rotating unit 1 and rotate theinserting device 9. For example, the releasable connection may beprovided by the coil removing device, which (in this embodiment) is ableto engage the inserting device 9 when in lowered position to connectthis device to unit 1.

An important feature of the present invention is that the rotating unit1 is angularly displaced so as to locate it at an angular positionshifted by one lobe relative to the position at the first multi-lobedcoil C₁ (which is in a stationary position on the inserting device 9)before activating the forming stage of the second polygonal coil C_(P1)by rotating in the opposite direction unit 1 and simultaneously rotatingthe inserting device 9. This condition is shown in FIG. 4, where themulti-lobed coil C₁ (which has been already discharged on t he insertingdevice 9) is shown with dotted lines. The forming elements 3 and theflat fingers 8 are at angular positions shifted by 30° relative to thefirst multi-lobed coil C₁, so that each forming element 3 is at anangular position corresponding for that of a hollow between adjacentlobes of the first multi-lobed coil C₁ already discharged on theinserting device 9.

A further feature which distinguishes the invention from the prior art,lies in that on one of the flat fingers 8 there is fixed an auxiliarywire engaging element 14 (see FIGS. 1 and 4) which is carried by unit 1and is coupled thereto at a radially fixed position. Specifically, thewire engaging element 14 is at a radial position corresponding to theradial position of the lobes of the coil. In particular, wire engagingelement 14 has an outer profile substantially corresponding to theprofile of a lobe. Furthermore, the wire engaging element 14 ispositioned such that after the previously formed first multi-lobed coilC₁ has been discharged on the inserting device 9, tile wire portionW_(i) connecting coil C₁ (positioned on the inserting device 9) to thewire feeding delivery tube 2 outlet mouth is intercepted by the wireengaging element 14 when the rotating unit 1 is rotated in ananti-clockwise direction (with reference to FIG. 5) in order to form asecond coil.

Therefore, the wire portion connecting the first multi-lobed coil C₁ tothe polygonal coil C_(P) being formed is intercepted by the wireengaging element 14 during the formation of the second polygonal coilC_(P2), as shown in FIGS. 1, 4 and 5. With reference to FIG. 1, it isalso to be noted that the inserting device 9 has been shown in acondition spaced axially from the rotating unit 1 for the sake ofclarity. Actually, the inserting device is located immediately below therotating unit, so that the intermediate wire portion W_(i) has a lengthmuch smaller than that shown in this figure. As shown in FIGS. 7 and 8,the first multi-lobed coil C₁ has a starting terminal end 15 and a finalterminal end 16 projecting from a hollow W_(f) of the multi-lobed coilC₁. The terminal end 16 extends radially and is curved into a portion 17(FIGS. 7 and 8) as a result of the wire W being intercepted by the wireengaging element 14 after rotating unit 1 starts rotating in theopposite direction (see FIGS. 1 and 5).

When the second polygonal coil C_(P2) has been formed (FIGS. 1 and 5)the rotating unit 1 is again stopped and the pushing members 6 are againdriven to push against the sides of the polygonal coil C_(P), therebytransforming the latter into a second multi-lobed coil C₂. In thisstage, the wire portion W_(i) projecting from the wire engaging element4 is intercepted by one of the pushing members 6a, causing it to bendinto a portion 18 (FIGS. 7 and 8) directed radially inwardly. Therefore,with reference to FIGS. 7 and 8, the wire portion W_(i) connecting thefirst multi-lobed coil C₁ to the second multi-lobed coil C₂ (which isangularly offset by one lobe relative to coil C₁) is bent to form a loopE (FIGS. 7 and 8) where the wire reverses its winding direction, with aportion following the profile of hollow V_(f) of coil C₁ and a portionfollowing the profile of a lobe L_(i) of the multi-lobed coil C₂. Thismeans that the two multi-lobed coils C₁ and C₂ are obtained withoutcutting the wire, and without the intermediate wire portion W_(i) havingredundant portions which might cause difficulties during the followingstage of insertion of the winding into the slots of a stator. Thewinding obtained thereby has a single startitng end 15 and a singlefinal end 19. As indicated above, it should be noted that in FIG. 7, theintermediate wire portion W_(i) which is shaped into a loop has beenshown in a deformed condition, with the two coils C₁ and C₂ axiallyspaced apart from each other, in order to show the loop configurationclearly. Actually, in the finally obtained winding, the two multi-lobedcoils C₁ and C₂ are located immediately above each other with theintermediate loop portion W_(i) lying substantially in a plane (FIG. 8).

Following the formation of the second multi-lobed coil C₂, the latter isnaturally discharged on the inserting device 9 by the blades of the coilremoving tool 13, similar to the first coil C₁.

In this manner, the winding obtained thereby and discharged on theinserting device 9 has two semi-phases C₁ and C₂ angularly shiftedrelative to each other by one lobe, which are obtained withoutinterrupting the wire and with two single terminal ends 15, 19.

According to the conventional art, once the inserting tool 9 hasreceived the finished winding, it is positioned at an inserting station,where a stator is preliminarily arranged for insertion of the winding.Typically, this is made in a machine with a rotating platform, carryingtwo inserting devices 9 which are located at diametrically oppositepositions so that they can be brought alternatively, by a 180° rotationof the rotating platform, at the two diametrically opposite stations,one of which is used for forming the winding and discharging the windingon the inserting device, the other station being a station for insertingthe winding into a stator. Therefore, an inserting device receives a newwinding while at the forming station, at the diametrically oppositestation another inserting device carrying a previously formed windingprovides for the insertion of this winding into a stator. When thisoperation is completed, the rotating structure is rotated by 180°, so asto arrange the inserting device which has previously inserted thewinding into a stator at the forming station, where it is ready toreceive a new winding, whereas the inserting device which has previouslyreceived a new winding provides for insertion thereof into anotherstator. These details of construction are not shown in the drawingssince, as previously indicated, they are known to the art.

FIG. 9 is a diagrammatic partial view of the inner cylindrical surfaceof a stator S having axial slots 20 for receiving radial portions of themulti-lobed coils constituting the winding. In this figure, as in FIG.8, the winding is shown in dotted lines, with the exception of the wireportion forming the loop E where the wire reverses its windingdirection. As shown in FIG. 8, the loop E follows an annular path whichfor one portion overlaps one lobe of a coil and another portion overlapsa hollow of the other coil opposite to the lobe. Therefore, in theinserting stage of the winding into stator S, the loop E does not causeany problems, since its portions 16, 18 may be received into two slots20 of stator S (FIG. 9).

In the embodiment disclosed in FIGS. 1-9, the rotating unit includes awire engaging element situated at a fixed position on the rotating unit.The position is chosen in such a way that the wire engaging elementintercepts the feeding wire when the rotation of the unit is reversed inorder to form the loop.

In order to further improve the previously proposed apparatus, anotherembodiment provides an apparatus having all the features indicatedabove, including the wire engaging element 14. However, the wireengaging element 14 is not located at a fixed position on the rotatingunit 1, but is connected instead to one of the forming elements 3 forforming the polygonal coil with which the rotating unit is provided.That forming element is movable in a radial direction relative to therotating unit.

Tests have shown that by providing the wire engaging element on one ofthe forming elements which are radially movable relative to the rotatingunit and are displaced towards the axis of rotation of this unit duringthe operation giving a star-like shape to the initially polygonal coil,it is ensured that a winding of a high quality is obtained, particularlyat the loop, where the wire reverses its winding direction.

In particular, tests have shown that the invention enables the loop tobe obtained precisely with the required circumferential extension, i.e.,neither with an excessively abundant length (which might disturb thesubsequent inserting operation of the winding into the slots of a statorof an alternator), nor with a length smaller than the theoretical one(which might give raise to an undesired tension on the wire in thesubsequent winding operation).

FIGS. 10, 11 and 12 are identical (except for the features which will bedescribed in the following) to FIGS. 1, 4 and 5 so that the descriptionthereof will not be repeated herein in detail. In the following, onlythe differences of the apparatus according to the present embodimentrelative to the apparatus of FIGS. 1-9 will be described.

FIG. 10 differs from FIG. 1 in that the wire engaging element 14 (onwhich the loop E is formed when the wire reverses its winding direction)comprises a plate screwed to the radial inner surface of one of theforming elements 3, rather than being fixed to one of the fixed blades 8carried by the rotating unit 1. This feature is also visible in FIGS. 11and 12. These figures are similar, as indicated, to FIGS. 4 and 5. FIGS.11 and 12 respectively show diagrammatically the apparatus in a planview after winding the first coil and after the beginning of the windingin the opposite direction of the second coil. As already discussed,apart from this difference, the structure and the operation of theapparatus are similar to that described in connection with FIGS. 1-9.

The operation of the wire engaging element 14 will be described withgreater particularity with reference to FIGS. 13 and 14. FIG. 13 is apartial diagrammatic plan view of the apparatus. It should be notedthat, for purposes of clarity, forming element 3 and wire engagingelement 14 are shown radially closer to the center of the rotating unit1 then they would be in actual practice. FIG. 14 is a partial view ofthe apparatus of FIG. 13 along A--A at a different stage of the formingoperation of the multi-lobed winding.

As shown in FIG. 13, the first multi-lobed coil C₁ has been inserted onthe blades 10 of the inserting tool 9 with the wire lead W_(z) extendingto the delivery tube 2 at angular position α. When the first multi-lobedcoil C₁ is deposited on the inserting tool 9, forming element 3 and wireengaging element 14 (wire engaging element 14 is connected to one of theforming elements 3, as shown in FIGS. 13 and 14) are in position P.Position P corresponds to the lobe of the first multi-lobed coil C₁immediately to the right of the delivery tube 2, as shown in FIG. 13.During the deposit of the first multi-lobed coil C₁ on the insertingtool 9, rotating unit 1 is lowered and delivery tube 2 reaches itslowest level h₁ (as shown in FIG. 14). Lowering the rotating unit 1facilitates deposit while lowering the delivery tube 2 prevents the wirelead W_(z) from becoming too long.

After the deposit of the first multi-lobed coil C₁ on the inserting tool9, rotating unit 1 and delivery tube 2 are raised (in order that wireengaging element 14 does not catch wire lead W_(z)) and rotated indirection D such that forming element 3 and wire engaging element 14 areat angular position β. As shown in FIG. 14, the tip of wire engagingelement 14 preferably slopes downward (in direction D) to furtherdecrease the chance of wire engaging element 14 catching wire lead W_(z)during the rotation in direction D to angular position β. Once atangular position β, rotating unit 1 arid delivery tube 2 are loweredtoward the inserting tool 9 and rotated in direction D₁ until wireengaging element 14 engages wire lead W_(z).

After wire engaging element 14 engages wire lead W_(z), rotating unit 1and the inserting tool 9 start to rotate in synchronism in direction D₁to form the second polygonal coil C_(P2). At about this time (i.e.,about when the synchronized rotation starts), rotating unit 1 rises awayfrom the inserting tool 9. The delivery tube 2 must also rise (to levelh₂, as shown in FIG. 14) in order to cause the wire of the secondpolygonal coil C_(P2) to engage forming elements 3 (which are higherthan wire engaging element 14).

Tests show that, due to the above indicated difference, the apparatusaccording to the present embodiment is able to provide a winding inwhich the loop formed by the wire where the wire reverses its windingdirection has a circumferential extension which substantiallycorresponds to the desired theoretical one, or at most slightly greater(to avoid any inconvenience both during the forming operation of thecoil and during the following inserting operation of the winding intothe slots of the stator of an alternator).

Merely by way of example, FIG. 10 shows the application of the apparatusto the case in which two wires are simultaneously wound on the rotatingunit 1. This technique, known in the art, provides for the use of a wirefeeding delivery tube 2 to which two separate wires W are fed fromseparate supplying reels and reach the rotating unit by passing throughtwo separate holes 2a, 2b (FIG. 11) of the feeding device 2, which keepthem spaced apart from each other by a given length. Naturally, theapparatus according to the present invention may also be used with afeeding device which feeds a single wire.

The invention is applicable both to the case in which a single wire iswound on the rotating unit, and to the case, corresponding to a knowntechnique, in which two wires are simultaneously fed by the feedingdevice which are simultaneously wound on the rotating unit, as shown inFIG. 10, for example.

Naturally, while the principle of the invention remains the same, thedetails of construction and the embodiments may widely vary with respectto what has been described and illustrated, without departing from thescope of the present invention.

In particular, the invention has been illustrated applied to a machineof the type shown in Italian patent 1,157,040, and in parallel U.S. Pat.No. 4,512,376, merely by way of example. At present, machines forforming undulatory coils are being used which are also of a typedifferent from that forming the subject of these prior patents and theprinciples which are at the basis of the present invention are equallyapplicable also to this type of machine. One skilled in the art willtherefore appreciate that the present invention can be practiced byother than the described embodiments, which are presented for purposesof illustration and not of limitation, and that the present invention islimited only by the claims which follow.

What is claimed is:
 1. An apparatus for forming a multi-lobed winding,the winding comprising turns defining a star-shaped configuration andhaving a plurality of radial lobes alternated with hollows, theapparatus comprising:a rotating unit for winding the wire, for forming apolygonal coil; pushing members carried by the rotating unit and movableradially with respect to the axis of rotation of the rotating unit,adapted to push the central portions of the sides of the polygonal coilradially inwardly, thereby forming the multi-lobed winding; and areceiving tool which is arranged coaxially with the rotating unit andwhich is capable of being rotated in synchronism with the rotating unit;wherein the multi-lobed winding is discharged on the receiving tool. 2.The apparatus of claim 1 further comprising:means for forming a secondmulti-lobed coil axially superimposed on the first coil, without cuttingthe wire being fed, by winding the wire in the opposite direction; meansfor arranging the second coil at a position angularly shifted relativeto the first coil, so that the second coil has its lobes at the sameangular positions of the hollows of the first coil; and means forbending the wire portion connecting the two coils where the wirereverses its winding direction, so as to form a loop following anannular path matching the profile of one lobe of one of the two coilsfor one part and the profile of a hollow of the other coil opposite tothe lobe for another part.
 3. The apparatus of claim 1 furthercomprising:means for forming a second multi-lobed coil axiallysuperimposed on the first coil, without cutting the wire being fed;means for arranging the second coil at a position angularly shiftedrelative to the first coil; and means for bending the wire portionconnecting the two coils, so as to form a wire portion connecting thefirst and second coils.
 4. The apparatus of claim 3 furthercomprising:means for rotating the rotating unit, subsequent todischarging the multi-lobed coil on the receiving tool, without cuttingthe wire, so as to form a second polygonal coil which is then shapedaccording to a multi-lobed configuration; and means for rotating thereceiving tool carrying the first multi-lobed coil, during forming ofthe second coil in synchronism with the rotating unit, but at a positionangularly shifted relative thereto; whereby the first and second coilsare obtained by a continuous process starting from the same wire.
 5. Theapparatus of claim 2 further comprising:means for rotating the rotatingunit, subsequent to discharging the multi-lobed coil on the receivingtool in the direction opposite to the direction of rotation in theforming stage of the coil, without cutting the wire, so as to form asecond polygonal coil which is then shaped according to a multi-lobedconfiguration; and means for rotating the receiving tool carrying thefirst multi-lobed coil, during forming of the second coil in synchronismwith the rotating unit, but at a position angularly shifted relativethereto, so that the second multi-lobed coil has its lobes where thehollows between the lobes of the first coil are located; whereby thefirst and second coils are obtained by a continuous process startingfrom the same wire, with the wire in the second coil having a windingdirection opposite to the winding direction of the wire in the firstcoil and with the wire portion connecting the first coil to the secondcoil forming the loop.
 6. The apparatus of claim 5 wherein the rotatingunit includes a wire engaging element at a fixed position on therotating unit, so that the wire engaging element intercepts the wirebeing fed when the rotation of the unit is reversed in order to form theloop.
 7. A method for forming a multi-lobed winding, the windingcomprising turns defining a star-shaped configuration and having aplurality of radial lobes alternated with hollows, the methodcomprising:forming a polygonal coil with a rotating unit; pushing thecentral portions of the sides of the polygonal coil radially inwardly,thereby forming the multi-lobed winding; and discharging the multi-lobedwinding on a receiving tool which is arranged coaxially with therotating unit and which is capable of rotating in synchronism with therotating unit.
 8. The method of claim 7 further comprising:forming asecond multi-lobed coil axially superimposed on the first coil, withoutcutting the wire being fed, arranging the second coil at a positionangularly shifted relative to the first coil.
 9. The method of claim 7further comprising:forming a second multi-lobed coil axiallysuperimposed on the first coil, without cutting the wire being fed, bywinding the wire in the opposite direction, arranging the second coil ata position angularly shifted relative to the first coil, so that thesecond coil has its lobes at the same angular positions of the hollowwas of the first coil, the wire portion connecting the two coils beingbent where the wire reverses its winding direction, so as to form a loopfollowing an annular path matching the profile of one lobe of one of thetwo coils for one part and the profile of a hollow of the other coilopposite to the lobe for another part.
 10. A method for forming amulti-lobed winding for the stator of an alternator comprising:forming apolygonal coil by winding a wire on a rotating unit; stopping therotating unit and pushing the central portions of the sides of thepolygonal radially inwardly so as to confer a multi-lobed configurationto the coil; discharging the multi-lobed coil on a receiving toolarranged coaxially with the rotating unit; rotating the rotating unit inthe direction opposite to the direction of rotation used to form thefirst coil, without cutting the wire being fed, so as to form a secondpolygonal coil which is then shaped according to a multi-lobedconfiguration; driving the receiving tool carrying the first multi-lobedcoil in synchronism with the rotating unit, but at a position angularlyshifted relative thereto, so that the second multi-lobed coil has itslobes where the hollows between the lobes of the first coil are located;whereby the first and second coils are obtained by a continuous processstarting from the same wire, with the wire in the second coil having awinding direction opposite to the winding direction of the wire in thefirst coil and with the wire portion connecting the first coil to thesecond coil forming the loop.
 11. A method for forming a multi-lobedwinding for the stator of an alternator comprising:forming a polygonalcoil by winding a wire on a rotating unit; stopping the rotating unitand pushing the central portions of the sides of the polygonal radiallyinwardly so as to confer a multi-lobed configuration to the coil;discharging the multi-lobed coil on a receiving tool arranged coaxiallywith the rotating unit; rotating the rotating unit, without cutting thewire being fed, so as to form a second polygonal coil which is thenshaped according to a multi-lobed configuration; driving the receivingtool carrying the first multi-lobed coil in synchronism with therotating unit, but at a position angularly shifted relative thereto;whereby the first and second coils are obtained by a continuous processstarting from the same wire.
 12. An apparatus for forming a multi-lobedwinding, the winding comprising turns defining a star-shapedconfiguration and having a plurality of radial lobes alternated withhollows, the apparatus comprising:a rotating unit for winding the wirebeginning at a starting end, for forming a polygonal coil; pushingmembers carried by the rotating unit and movable radially with respectto the axis of rotation of the rotating unit, adapted to push thecentral portions of the sides of the polygonal coil radially inwardly,thereby forming the multi-lobed winding; a receiving tool which isarranged coaxially with the rotating unit and which is capable of beingrotated in synchronism with the rotating unit, wherein the multi-lobedwinding is discharged on the receiving tool; means for forming a secondmulti-lobed coil axially superimposed on the first coil, without cuttingthe wire being fed, by winding the wire in the opposite directionbeginning at a hollow offset by one lobe relative to the starting end;means for arranging the second coil at a position angularly shiftedrelative to the first coil, so that the second coil has its lobes at thesame angular positions of the hollows of the first coil; and means forbending the wire portion connecting the two coils where the wirereverses its winding direction, so as to form a loop following anannular path matching the profile of one lobe of one of the two coilsfor one part and the profile of a hollow of the other coil opposite tothe lobe for another part.
 13. The apparatus of claim 12 furthercomprising:means for rotating the rotating unit, subsequent todischarging the multi-lobed coil on the receiving tool in the directionopposite to the direction of rotation in the forming stage of the coil,without cutting the wire, so as to form a second polygonal coil which isthen shaped according to a multi-lobed configuration; and means forrotating the receiving tool carrying the first multi-lobed coil, duringforming of the second coil in synchronism with the rotating unit, but ata position angularly shifted relative thereto, so that the secondmulti-lobed coil has its lobes where the hollows between the lobes ofthe first coil are located; whereby the first and second coils areobtained by a continuous process starting from the same wire, with thewire in the second coil having a winding direction opposite to thewinding direction of the wire in the first coil and with the wireportion connecting the first coil to the second coil forming the loop.14. The apparatus of claim 13 wherein the rotating unit includes a wireengaging element at a fixed position on the rotating unit, so that thewire engaging element intercepts the wire being fed when the rotation ofthe unit is reversed in order to form the loop.
 15. A method for forminga multi-lobed winding, the winding comprising turns defining astar-shaped configuration and having a plurality of radial lobesalternated with hollows, the method comprising:forming a polygonal coilbeginning at a starting end with a rotating unit; pushing the centralportions of the sides of the polygonal coil radially inwardly, therebyforming the multi-lobed winding; discharging the multi-lobed winding ona receiving tool which is arranged coaxially with the rotating unit andwhich is capable of rotating in synchronism with the rotating unit;forming a second multi-lobed coil axially superimposed on the firstcoil, without cutting the wire being fed, by winding the wire in theopposite direction beginning at a hollow offset by one lobe relative tothe starting end, arranging the second coil at a position angularlyshifted relative to the first coil, so that the second coil has itslobes at the same angular positions of the hollows of the first coil,the wire portion connecting the two coils being bent where the wirereverses its winding direction, so as to form a loop following anannular path matching the profile of one lobe of one of the two coilsfor one part and the profile of a hollow of the other coil opposite tothe lobe for another part.
 16. A method for forming a multi-lobedwinding for the stator of an alternator comprising:forming a polygonalcoil by winding a wire on a rotating unit beginning at a starting end;stopping the rotating unit and pushing the central portions of the sidesof the polygonal coil radially inwardly so as to confer a multi-lobedconfiguration to the coil; discharging the multi-lobed coil on areceiving tool arranged coaxially with the rotating unit; rotating therotating unit in the direction opposite to the direction of rotationused to form the first coil, without cutting the wire being fed, so asto form a second polygonal coil beginning at a hollow offset by one loberelative to the starting end which is then shaped according to amulti-lobed configuration; driving the receiving tool carrying the firstmulti-lobed coil in synchronism with the rotating unit, but at aposition angularly shifted relative thereto, so that the secondmulti-lobed coil has its lobes where the hollows between the lobes ofthe first coil are located; whereby the first and second coils areobtained by a continuous process starting from the same wire, with thewire in the second coil having a winding direction opposite to thewinding direction of the wire in the first coil and with the wireportion connecting the first coil to the second coil forming the loop.